With the development of wireless network technologies, different wireless networks emerge, such as macro cell (Macro cell), pico cell (Pico cell), femto cell (Femto cell). Each cell can serve a certain area where a user equipment (User Equipment, UE) is located. Each base station can manage a plurality of cells. Transmit power and coverage of different base stations are different. Where, for a high-power base station (such as a macro base station), transmit power is relatively high and coverage is relatively large, for example, generally, transmit power of a macro base station is tens of watts and a coverage radius is 500˜1000 m; and for a low-power base station (such as a Femto base station or a Pico base station), transmit power is relatively low and coverage is relatively small, for example, generally, a coverage radius of a Femto base station is about 10 m. A base station communicates with a UE through a downlink and an uplink, where a one-way communication link from the base station to the UE is referred to as a downlink, and a one-way communication link from the UE to the base station is referred to as an uplink.
On a heterogeneous network including a plurality of wireless networks, for the same electromagnetic wave resource, cells of different wireless networks may interfere with each other, which consequently deteriorates signal quality of cells that interferes with each other. To prevent and coordinate cell interference, transmission synchronization between interfering cells must be implemented at first, and further interference can be avoided through upper-layer resource scheduling. For a network by using an orthogonal frequency division multiple (Orthogonal Frequency Division Multiple, OFDM) transmission technology, a requirement for transmission synchronization is relatively strict. It is required that a transmission synchronization error is within one cycle prefix (Cycle Prefix, CP).
In the prior art, synchronization between base stations is mainly used to solve a problem of synchronization between a low-power base station that needs to adjust synchronization time and a high-power base station that serves as a synchronization time reference. Its main concept is to take the low-power base station that needs to adjust synchronization time and its coverage as a point for processing. Therefore, an applicable range of this method is limited. This method can apply only to synchronization between a low-power base station that needs to adjust synchronization time and a high-power base station that serves as a synchronization time reference, and cannot apply to other base station synchronization scenarios.